One aspect of the invention relates to a semiconductor component having a semiconductor body, the semiconductor body including a substrate of a first conduction type, a buried semiconductor layer of a second conduction type arranged on the substrate, a functional unit semiconductor layer of a third conduction type arranged on the buried semiconductor layer, in which at least two semiconductor functional units arranged laterally alongside one another are provided, and a contact from a surface of the semiconductor body to the substrate. The buried semiconductor layer is a part of at least one semiconductor functional unit. The semiconductor functional units are electrically insulated from one another by an isolation structure, which permeates the functional unit semiconductor layer, the buried semiconductor layer and also the substrate.
The lateral space requirement of semiconductor components of the type mentioned in the introduction is relatively large. This stems inter alia from the fact that the isolation structures which permeate the functional unit semiconductor layer, the buried semiconductor layer and also the substrate are produced on the basis of a diffusion process. For example, in order to produce the isolation structures, prior to producing the buried semiconductor layer, dopants are introduced into the upper region of the substrate and, after producing the buried semiconductor layer and the functional unit semiconductor layer, dopants are introduced into the upper region of the functional unit semiconductor layer (above the region of the substrate into which dopants were introduced). Afterward, the two dopant regions are caused to melt by means of a heat treatment process, that is to say that the vertical extents of the dopant regions are enlarged until the latter vertically overlap one another.
An isolation structure produced in this way can be seen in FIG. 1A. A semiconductor body 1 has a substrate 2, a buried semiconductor layer 3 arranged on the substrate 2, and a functional unit semiconductor layer 4 arranged on the buried semiconductor layer 3. The functional unit semiconductor layer 4, the buried semiconductor layer 3 and also the substrate 2 are permeated by an isolation structure 51 (Junction Isolation), which serves for isolating a semiconductor functional unit (not shown) arranged on the left alongside the isolation structure 51 from a semiconductor functional unit (not shown) arranged on the right alongside the isolation structure 51. The conduction type of the functional unit semiconductor layer 4 and of the buried semiconductor layer 3 is of a first conduction type (for example of the n conduction type), whereas the semiconductor material which the isolation structure 51 includes and the substrate 2 are of a second conduction type (for example of the p conduction type). Thus, the isolation structure 51 simultaneously serves as a contact to the substrate 2. The isolation structure 51 has a first isolation structure region 51 and a second isolation structure region 52, which are produced by introducing dopants into the upper region of the substrate 2 and also into the upper region of the functional unit semiconductor layer 4 and a subsequent heat treatment process. The heat treatment process has the effect of enlarging the lateral extent of the isolation structure regions 51, 52, which is undesirable since the resultant lateral space requirement of the semiconductor component is enlarged unnecessarily.
Trench isolations 52 are furthermore known as isolation structures (FIG. 1B). In this case, a trench 11 extending from the surface 41 of the semiconductor component 1 right into the substrate 2 is configured in such a way that it electrically insulates adjacent semiconductor functional units (not shown) in the functional unit semiconductor layer 4 from one another. The trench 11 may be filled with an insulating material (not shown). It is likewise possible to form an insulating layer 12 on the sidewalls and the bottom of the trench 11 and to fill the trench 11 with polysilicon 17, for example, as illustrated in FIG. 1B.
However, the known isolation by means of trenches, as illustrated in FIG. 1B, does not afford a possibility of making contact with the substrate as in the case of diffusion isolation described with reference to FIG. 1A. Therefore, the contact connection to the substrate has to be produced for example by means of an additional diffusion zone or via a rear side contact.